Electromagnetic device with armature



May 4, 1948. c. BIGGLE ELECTROMAGNETIC DEVICE WITH ARMATURE Filed Feb. 20, 1945 Bnnentor:

LAURENCE C. BIGG Bu I Gttomeg.

Patented May 4, 1948 2,440,888 ELECTROMAGNETIC nnvron wrrn ABMA'IURE 'Laurence C. Biggie, Altadena, Calm, assignor to General Controls (10., Glendale, Colin, a corpo- California ration of Application February 20, 1945, Serial No. 578,827 9 Claims. (Cl. 175-336) My present invention relates to electromagnetic devices of the type which comprises a rockable armature for operating electrical contacts, pilot-valve means, or the like.

It is an object of this invention to provide a deviceof the character described which is so constructed that transfer of magnetic flux between the armature and the core of the device is improved.

More specifically it is an object to provide an electromagnetic device comprising a U-shaped core and an armature fulcrumed on the end of one of the side arms of the core, and means for increasing -fiux transfer between the armature and the fulcrum end of the core without adversely affecting mechanical movement of the armature.

Another object is to provide, in a device of the character described'in the preceding object, improved means forretaining the armature in operative relation to the core. I

Still anotherobject is to provide improved means for preventing relative flexure of the side arms of the U-shaped core.

Other objects and advantages of the invention will be found in the description, thev drawing, and the claims; and, for full understanding of the invention, reference is to be had to the following detailed description and accompanying drawing, wherein:

Figure 1 is a perspective view of an electromagnetic device embodying the invention:

Figure 2 is an exploded view of. the device shown in Fig. 1;

Figure 3 is an enlarged side elevation of the device of Fig. 1 as mounted on a base, the bracket 28 and. armature-retainingclip 24 being shown in section;

Figure 4 is a detail view of the pole piece it; and

Fig. 5 is a fragmentary bottom view of the structure shown in Fig. 3.

Referring first more particularly to Fig. 2 of the drawing, the numeral l l indicates a generally U-shaped electromagnet core having 8. rectangular lower side-arm i2 and a cylindrical upper side-arm I3 which are Joined by a triangular end portion H; the parts preferably being integrally formed from a single piece of metal so as to avoid the possibility of air-gap losses. Around the upper side-arm i3 is an energizing coil [5; the mean turn diameter (and, consequently, the electrical resistance) of the winding of this coil being relatively small due to the small diameter of the arm (3,- as indicated in the drawis mounted, the pole piece is directly upwardly from its ing.. On the end of arm I3 is a pole piece It (shown per se in Fig. 4) having an opening for tightly receiving the arm so that, after the coil pressed-on to a position wherein its outer surface, or pole face, is exactly aligned with the end of the lower arm (2. Closely fitting the pole piece I 6, and in abutting relation to shoulders I! (Fig. 4) formed on opposite sides thereof, is a plate 18 of non-magnetizable metal.

At the end of the lower side-arm l2 of the core, and preferably formed integrally therewith, is a lateral extension IS. The ends of arm l2 and extension I! are oppositely beveled to form, respectively, inclined surfaces 20 and 21 which define between them a knife-edge fulcrum 22. This fulcrum, while conveniently termed as knifeedged, is preferably quite blunt and has a surface or land of about 0.020 inch in width The fulcrum 22 serves as a support for a bladelike armature 23 which is retained in position with respect to the core by a generally U-shaped wire clip 24, the side arms of the clip extending freely through notches 25 in opposite edges of the armature and into grooves 26 formed in the extension l9 adjacent the fulcrum 22. The grooves 26 are of such size that the clip fits snugly within them so that the clip is held temporarily in armature-retaining position during assembly. For convenience of handling, the clip is provided with a forked projection 21.

Generally indicated at 28 in Fig. 2 is a bracket, preferably formed of non-magnetizable material such as brass. To attach this bracket to the electromagnet core (after the armature and retaining clipare in position) the bracket is moved position as shown in Fig. 2, the lower portion of the armature passing through the rectangular opening 29. Formed at opposite sides of the bracket opening 29 are recesses 30 which are adapted to receive and hold the outwardly-bent extremities 3| of the side arms of the armature-retaining clip 24 when the bracket is inits final position (as shown in Fig. 1) in engagement with the underside of the lower side-arm P2 of the core. The bracket 28 has a pair of upstanding (as seen in Fig. 2) arms 32 which are flexed slightly apart, during assembly of the bracket, to permit their channeled upper portions to receive lugs 33 formed on opposite sides of the plate i8; these lugs, when the bracket reaches its final position, snapping into conforming openings 34 in the bracket arms. When the bracket is in position, it is secured to the core by screws 35 (Fig. 3) which pass through openings A also being shown ing the jets.

I minute distance larly, the surface 20 said material of said one a in the bracket and are threaded incorresponding openings in the core side-arm l2. The device. as assembled, is shown in Fig. 1. By the cooperation of the bracket side-arms 32 with the plate It, relative movement of the core sidearms, such I is prevented; accurate alignment of the polar surface of pole piece it with the fulcrum 22 thus being preserved.

In Fig. 3, the electromagnetic device is shown mounted on an apertured base plate 81; there in this iigure'a pair of jets 38 and 39 with which the lower end portion of the armature cooperates to serve as 'the closure of a conventional three-way pilot valve compris- This arrangement is only by way of illustration and obviously other control means, such as electrical contacts, could be substituted for the Jets. As shownin Fig. 3, the armature 23 is biased into engagement with Jet 38, and with the fulcrum 22, by theforce of a compression spring 40 which is clamped at one end to the base plate 31 by an upset portion ll of the bracket 28, the pointed other end of the spring resting in a small depression 42 (Fig.2) in the armature. When the core ii is energized by passage of current engagement with the other jet 38; the armature then being slightly, spaced from the pole piece.

As is seen in Fig, 3, the surface 2| (Fig. 2) defined by the extension I9 is spaced by only a from the armature when the same is in its unattracted position, 'so that conduction of magnetic flux adjacent the fulcrum is increased and the pull-in value of the energizing current correspondingly decreased. Simiat the opposite side of the fulcrum is inclined at only a small angle. For the sake of clarity, the angles of inclination of the surfaces 20 and 2!, as shown in the drawing, have been exaggerated; the inclination of these surfaces, in a practical embodiment of the invention, being such that the space between the armature and the outer extremity of surface M is about 0.002 inch, and that at surface 20 about 0.010 inch, when the armature is rocked toward the respective surfaces. Due to this arrangement of the polar surfaces 20 and 2|, and also due to the enlarged polar surface provided by the pole piece it, the effectiveness and sensitivity of the device is considerably increased.

The specific embodiment of my invention herein shown and described is obviously susceptible of modification without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In an electromagnetic device: a generally U-shaped core, an energizing coil for said core, and a blade-like armature rockably supported on the end of one of the side arms of the core and extending adjacent the end of the other of the side arms for attraction theretoward when the core is energized, the end of said one of the side arms being formed to provide a fixed knife-edge fulcrum for the armature, the material of said one of the side arms on the side of said fulcrum away from the other of the side arms providing a fiat surface spaced by a minute distance from the armature when, upon deenergization of the core, the armature is rocked toward said surface, of the side arms being so intimately united with the remainder of the through coil it, the armature is attracted toward the pole piece it and into direction away from side arm that there is no air-gap therebetween. 2. In an electromagnetic device: a generally u-shaped core, an energizing coil for said core, and a blade-like armature rockably supported on the end of one of the side arms of the core andextending adjacent the end of the other of the side arms for attraction theretoward when the core is energized, the end of said one of the side arms beig formed to provide a fixed fulcrum for the armature, said one ing at said end thereof a lateral extension in a the other of the side arms. said extension being of magnetizable material and providing a flat surface of relatively large area spaced by a minute distance from a portion of the armature when, upon deenergization of the core, the armature is rocked toward said surface, said extension being so intimately united with the side arm from whichit extends that there is no air-gap therebetween.

extending adjacent the end of the other of the side arms for attraction theretoward when the core is energized, the end of said one of the side arms being formed to provide a fixed knife-edge fulcrum for the armature, the material of said one of the side arms being intimately united with the side arm and beveled to provide a pair of inclined flat surfaces on opposite sides of said knife-edge, the one of said surfaces away from said other of the side arms being relatively large in area and spaced by a minute distance from the armature when, upon deenergization of the core, the armature is rocked theretoward.

4. In an electromagnetic device: a generally U-shaped core, an energizing coil for said core, and a blade-like armature rockably supported on the end of one of the side arms of the core and extending adjacent the end of the other of the side arms for attraction theretoward when the core is energized, the end of said one of the side arms being formed to provide a fixed knife-edge fulcrum for the armature, the material of said one of the side arms being intimately united with the side arm and beveled to provide a pair, of inclined flat surfaces on opposite sides of said knife edge, said material being so extended in a direction away from the other of the side arms that the one of said surfaces there defined is of relativelylarge area, said one of the surfaces being spaced by a minute distance from a portion of the armature when, upon deenergization of thecore, the armature is rocked theretoward.

5. In an electromagnetic device: a generally ti -shaped core, an energizing coil for said core, and a bladedilre armature rockably supported on the end of one of the side arms of the core and extending adjacent the end of the other of the side arms for attraction theretoward when the coreis energized, the end of said one of the side arms being formed to provide a fixed knife-edge fulcrum for the armature, said one of the side arms having at said end t erect a lateral extension in a direction from the other of the side arms, said extension being integral with the side arm and providing a fiat surface of relatively large areaspaced by a minute distance from a portion of the armature when, upon deenergization of the core, the armature is rocked theretoward, said end of the other of the side arms being formed to provide a surface having a large of the side arms havarea in flux-transfer suriace or the armatur 6. In an electromagnetic device: a generally U-shaped core; an energizing coil for said core; a blade-like armature rockably supported on the end of one of the side arms of the core and extending adjacent the end 01' the other oi. the side arms for attraction theretoward when the core is energized; and retaining means for the arms.- ture, comprising a generally U-shaped clip the side arms of which freely extend through openings formed at opposite margins of the armature on the pivotal axis thereei' openings in the corresponding margins of said one of the eore side-arms,

7. In an eleetremegnetie device: generally U-shapeel eere; an energizing eeii fer said core; a blede like armature reehebiy segmented en the end ef ef the side nrms of t e eere and exntijneent the end of arms for and when core is energized; retain, memes fer the erme= U SllMml the side whieh freely extend oneh open inns the miniature on the nivetel thereof, end at iii" ehet ee= relation to the adjacent e.

tensed t ene the cere eiele n the free ends of e side 05: the eli e went; in the plane e5. the eiize, hr et nevlne r entwaidly lizent m AA z e: a blade "he end of en M,

tending l I e; emctten ereewe e1 whow and are mounted in v nee e2 the side on the pivotal axis thereof and are closely received in grooves formed in the corresponding margins of said one of the core side-arms and a bracket fastened to said one of the core sidearms, the free ends of the side arms or the clip being outwardly bent in the plane of the clip, said bracket having recessess for receiving said outwardly-bent end portions of the clip.

9. In an electromagnetic device: a. generally U-shaped eere: an energizing cell for said core; a blade-like armature rmkabiy supported on the end cf one at the side arms of the core and extending adjacent the end of the other of the side arms for attreetien thereteward when the core is energized; for preventing reiative fiexnre of stain side e eemnristng a plate taperan :Iit ever end of the ether of the me n he lens extending "is fer pic; e,

The ieliewing i'erenees are at reeerd the me ef this ether of ment with e ipesite Number nice ee 

